IBM ILOG CPLEX Optimizer Options for AMPL
--------------------------------------------
To set these options, assign a string specifying their values to the AMPL
option "cplex_options". For example:
ampl: option cplex_options 'mipgap=1e-6';
Options:
acc:indeq (acc:indlineq)
Solver acceptance level for 'IndicatorConstraintLinEQ', default 1:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:indge (acc:indlinge)
Solver acceptance level for 'IndicatorConstraintLinGE', default 1:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:indle (acc:indlinle)
Solver acceptance level for 'IndicatorConstraintLinLE', default 1:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:lineq
Solver acceptance level for 'LinConEQ', default 2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:linge
Solver acceptance level for 'LinConGE', default 2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:linle
Solver acceptance level for 'LinConLE', default 2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:linrange (acc:linrng)
Solver acceptance level for 'LinConRange', default 2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:pl (acc:pwl, acc:piecewise)
Solver acceptance level for 'PLConstraint', default 2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:quadeq
Solver acceptance level for 'QuadConEQ', default 2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:quadge
Solver acceptance level for 'QuadConGE', default 2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:quadle
Solver acceptance level for 'QuadConLE', default 2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:sos1
Solver acceptance level for 'SOS1Constraint', default 2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:sos2
Solver acceptance level for 'SOS2Constraint', default 2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
alg:barrier (barrier)
Solve (MIP root) LPs by barrier method.
alg:basis (basis)
Whether to use or return a basis:
0 - No
1 - Use incoming basis (if provided)
2 - Return final basis
3 - Both (1 + 2 = default)
alg:dual (dual)
Solve (MIP root) LPs by dual simplex method.
alg:feasrelax (feasrelax)
Whether to modify the problem into a feasibility relaxation problem:
0 = No (default)
1 = Yes, minimizing the weighted sum of violations
2 = Yes, minimizing the weighted sum of squared violations
3 = Yes, minimizing the weighted count of violations
4-6 = Same objective as 1-3, but also optimize the original objective,
subject to the violation objective being minimized.
Weights are given by suffixes .lbpen and .ubpen on variables and .rhspen
on constraints (when nonnegative, default values = 0), else by keywords
alg:lbpen, alg:ubpen, and alg:rhspen, respectively (default values = 1).
Weights < 0 are treated as Infinity, allowing no violation.
alg:iisfind (iisfind, iis)
Whether to find and export an IIS. Default = 0 (don't export).
alg:lbpen (lbpen)
See alg:feasrelax.
alg:method (method, lpmethod, simplex)
Which algorithm to use for non-MIP problems or for the root node of MIP
problems, unlessprimal/dual/barrier/network/sifting flags are specified:
-1 - Automatic (default)
0 - Primal simplex
1 - Dual simplex
2 - Barrier
3 - Nondeterministic concurrent (several solves in parallel)
4 - Network simplex
5 - Sifting
alg:network (network)
Solve (substructure of) (MIP node) LPs by network simplex method.
alg:primal (primal)
Solve (MIP root) LPs by primal simplex method.
alg:rays (rays)
Whether to return suffix .unbdd if the objective is unbounded or suffix
.dunbdd if the constraints are infeasible:
0 - Neither
1 - Just .unbdd
2 - Just .dunbdd
3 - Both (default)
alg:relax (relax)
0*/1: Whether to relax integrality of variables.
alg:rhspen (rhspen)
See alg:feasrelax.
alg:sifting (sifting)
Solve (MIP root) LPs by sifting method.
alg:start (warmstart)
Whether to use incoming primal (and dual, for LP) variable values in a
warmstart:
0 - No
1 - Yes (for LP: if there is no incoming alg:basis) (default)
2 - Yes (for LP: ignoring the incoming alg:basis, if any.)
alg:ubpen (ubpen)
See alg:feasrelax.
bar:crossover (crossover, mipcrossover)
How to transform a barrier solution to a basic one:
-1 - No crossover
0 - Automatic (default)
1 - Primal crossover
2 - Dual crossover
cvt:bigM (cvt:bigm, cvt:mip:bigM, cvt:mip:bigm)
Default value of big-M for linearization of logical constraints. Not
used by default. Use with care (prefer tight bounds). Should be smaller
than (1.0 / [integrality tolerance])
cvt:expcones (expcones)
0*/1: Recognize exponential cones.
cvt:mip:eps (cvt:cmp:eps, cmp:eps)
Tolerance for strict comparison of continuous variables for MIP. Applies
to <, >, and != operators. Also applies to negation of conditional
comparisons: b==1 <==> x<=5 means that with b==0, x>=5+eps. Default:
1e-4.
cvt:names (names, modelnames)
Whether to read or generate variable / constraint / objective names:
0 - No names
1 - (Default) Only provide names if at least one of .col / .row name
files was written by AMPL (AMPL: `option [<solver>_]auxfiles rc;`)
2 - Read names from AMPL, but create generic names if not provided
3 - Create generic names.
cvt:plapprox:domain (plapprox:domain, plapproxdomain)
For piecewise-linear approximated functions, both arguments and result
are bounded to +-[pladomain]. Default 1e6.
cvt:plapprox:reltol (plapprox:reltol, plapproxreltol)
Relative tolerance for piecewise-linear approximation. Default 0.01.
cvt:pre:all
0/1*: Set to 0 to disable most presolve in the flat converter.
cvt:pre:eqbinary
0/1*: Preprocess reified equality comparison with a binary variable.
cvt:pre:eqresult
0/1*: Preprocess reified equality comparison's boolean result bounds.
cvt:pre:unnest
0/1*: Inline nested expressions, currently Ands/Ors.
cvt:quadcon (passquadcon)
Convenience option. Set to 0 to disable quadratic constraints. Synonym
for acc:quad..=0. Currently this disables out-multiplication of
quadratic terms, then they are linearized.
cvt:quadobj (passquadobj)
0/1*: Multiply out and pass quadratic objective terms to the solver, vs.
linear approximation.
cvt:socp (socpmode, socp)
Second-Order Cone recognition mode:
0 - Do not recognize SOCP forms
1 - Recognize from non-quadratic expressions only (sqrt, abs)
2 - Recognize from quadratic and non-quadratic SOCP forms. Helpful if
the solver does not recognize non-standard forms
Recognized SOCP forms can be further converted to (SOCP-standardized)
quadratic constraints, see cvt:socp2qc. Default: 2.
cvt:socp2qc (socp2qcmode, socp2qc)
Mode to convert recognized SOCP forms to SOCP-standardized quadratic
constraints:
0 - Do not convert
1 - Convert if no other cone types found, and not all original
quadratics could be recognized as SOC, in particular if the
objective is quadratic
2 - Always convert
Such conversion can be necessary if the solver does not accept a mix of
conic and quadratic constraints/objectives. Default: 2.
cvt:sos (sos)
0/1*: Whether to honor declared suffixes .sosno and .ref describing SOS
sets. Each distinct nonzero .sosno value designates an SOS set, of type
1 for positive .sosno values and of type 2 for negative values. The .ref
suffix contains corresponding reference values used to order the
variables.
cvt:sos2 (sos2)
0/1*: Whether to honor SOS2 constraints for nonconvex piecewise-linear
terms, using suffixes .sos and .sosref provided by AMPL.
cvt:uenc:negctx:max (uenc:negctx:max, uenc:negctx)
If cvt:uenc:ratio applies, max number of constants in comparisons
x==const in negative context (equivalently, x!=const in positive
context) to skip UEnc(x). Default 1.
cvt:uenc:ratio (uenc:ratio)
Min ratio (ub-lb)/Nvalues to skip unary encoding for a variable x, where
Nvalues is the number of constants used in conditional comparisons
x==const. Instead, indicator constraints (or big-Ms) are used, if
uenc:negctx also applies. Default 0.
lim:time (timelim, timelimit)
limit on solve time (in seconds; default: no limit).
lp:solutiontype (solutiontype)
Whether to seek a basic solution when solving an LP:
0 - Automatic - seeks a solution with basis (default)
1 - Yes (equivalent to 0)
2 - No
mip:basis (fixmodel, mip:fix)
Whether to compute duals / basis / sensitivity for MIP models:
0 - No (default)
1 - Yes.
mip:bestbound (bestbound, return_bound)
Whether to return suffix .bestbound for the best known MIP dual bound on
the objective value:
0 - No (default)
1 - Yes.
The suffix is on the objective and problem and is -Infinity for
minimization problems and +Infinity for maximization problems if there
are no integer variables or if a dual bound is not available.
mip:gap (mipgap)
Relative optimality gap |bestbound-bestinteger|/(1e-10+|bestinteger|).
mip:nodemethod (nodemethod)
Algorithm used to solve relaxed MIP node problems; for MIQP problems
(quadratic objective, linear constraints), settings other than 3 and 5
are treated as 0. For MIQCP problems (quadratic objective and
constraints), only 0 is permitted.
0 - Automatic (default)
1 - Primal simplex
2 - Dual simplex
3 - Network simplex
4 - Barrier
5 - Sifting
mip:return_gap (return_mipgap)
Whether to return mipgap suffixes or include mipgap values (|objectve -
.bestbound|) in the solve_message: sum of
1 - Return .relmipgap suffix (relative to |obj|)
2 - Return .absmipgap suffix (absolute mipgap)
4 - Suppress mipgap values in solve_message.
Default = 0. The suffixes are on the objective and problem. Returned
suffix values are +Infinity if no integer-feasible solution has been
found, in which case no mipgap values are reported in the solve_message.
mip:round (round)
Whether to round integer variables to integral values before returning
the solution, and whether to report that the solver returned noninteger
values for integer values: sum of
1 ==> Round nonintegral integer variables
2 ==> Modify solve_result
4 ==> Modify solve_message
Default = 0. Modifications that were or would be made are reported in
solve_result and solve_message only if the maximum deviation from
integrality exceeded mip:round_reptol.
mip:round_reptol (round_reptol)
Tolerance for reporting rounding of integer variables to integer values;
see "mip:round". Default = 1e-9.
obj:*:abstol (obj_*_abstol)
Absolute tolerance for objective with index *. Can only be applied on a
multi-objective problem with obj:multi=1
obj:*:priority (obj_*_priority)
Priority for objective with index *
obj:*:reltol (obj_*_reltol)
Relative tolerance for objective with index *
obj:*:weight (obj_*_weight)
Weight for objective with index *
obj:multi (multiobj)
0*/1: Whether to use multi-objective optimization. If set to 1
multi-objective optimization is performed using lexicographic method
with the first objective treated as the most important, then the second
objective and so on.
obj:no (objno)
Objective to optimize:
0 - None
1 - First (default, if available)
2 - Second (if available), etc.
qp:target (optimalitytarget)
Type of solution to compute for a QP problem
sol:chk:fail (chk:fail, checkfail)
Fail on MP solution check violations, with solve result 150.
sol:chk:feastol (sol:chk:eps, chk:eps, chk:feastol)
Absolute tolerance to check objective values, variable and constraint
bounds. Default 1e-6.
sol:chk:feastolrel (sol:chk:epsrel, chk:epsrel, chk:feastolrel)
Relative tolerance to check objective values, variable and constraint
bounds. Default 1e-6.
sol:chk:infeas (chk:infeas, checkinfeas)
Check even infeasible solution condidates, whenever solver reports them.
sol:chk:inttol (sol:chk:inteps, sol:inteps, chk:inttol)
Solution checking tolerance for variables' integrality. Default 1e-5.
sol:chk:mode (solcheck, checkmode, chk:mode)
Solution checking mode. Sum of a subset of the following bits:
1 - Check variable bounds and integrality.
2 - Check original model constraints, as well as any non-linear
expression values reported by the solver.
4 - Check intermediate auxiliary constraints (i.e., those which were
reformulated further).
8 - Check final auxiliary constraints sent to solver.
16 - Check objective values.
32, 64, 128, 256, 512 - similar, but non-linear expressions are
recomputed (vs using their values reported by the solver.)
*Experimental.* This is an idealistic check, because it does not
consider possible tolerances applied by the solver when computing
expression values.
Default: 1+2+512.
sol:chk:prec (chk:prec, chk:precision)
AMPL solution_precision option when checking: number of significant
digits.
sol:chk:round (chk:round, chk:rnd)
AMPL solution_round option when checking: round to this number of
decimals after comma (before comma if negative.)
sol:count (countsolutions)
0*/1: Whether to count the number of solutions and return it in the
".nsol" problem suffix. The number and kind of solutions are controlled
by the sol:pool... parameters. Value 1 implied by sol:stub.
sol:poolgap (ams_eps, poolgap)
Relative tolerance for reporting alternate MIP solutions (default:
1e75).
sol:poolgapabs (ams_epsabs, poolagap)
Absolute tolerance for reporting alternate MIP solutions (default:
1e75).
sol:poolintensity (poolintensity)
How hard to try adding MIP solutions to the solution
pool. Useful only if poolstub is specified.
0 - Treated as 1 if poolstub is specified without populate, or 2 if
populate is specified (default)
3 - More additions to the solution pool
4 - Tries to generate all MIP solutions and keep the best
"sol:poollimit" ones.
sol:poollimit (ams_limit, poolcapacity, poollimit, solnlimit)
Limit on the number of alternate MIP solutions written. Default:
2100000000.
sol:poolmode (ams_mode, poolmode)
Search mode for MIP solutions when sol:stub/sol:count are specified to
request finding several alternative solutions. Overriden by sol:populate
andsol:poolintensity. Values:
0 - Just collect solutions during normal solve
1 - Make some effort at finding additional solutions =>
poolintensity=2, populate=1
2 - Seek "sol:poollimit" best solutions (default) => poolintensity=2,
populate=1
sol:poolpopulate (populate)
Whether to run CPLEX's "populate" algorithm in an attempt to add more
solutions to the MIP solution pool:
0 - no; just keep solutions found during the initial solve
1 - run "populate" after finding a MIP solution
sol:poolpopulatelim (populatelim)
Limit on number of solutions added to the solution pool by the populate
algorithm. Default: 20.
sol:poolreplace (poolreplace)
Policy for replacing solutions in the solution pool if more than
poolcapacity solutions are generated:
0 - FIFO (first-in, first-out); default
1 - Keep best solutions
2 - Keep most diverse solutions
sol:stub (ams_stub, solstub, solutionstub)
Stub for alternative MIP solutions, written to files with names obtained
by appending "1.sol", "2.sol", etc., to <solutionstub>. The number of
such files written is affected by the keywords poolgap, poolgapabs,
poollimit, poolpopulatelim, poolpopulate, poolintensity and poolmode.
The number of alternative MIP solution files written is returned in
suffix .nsol on the problem.
tech:bardisplay (bardisplay)
Specifies how much the barrier algorithm chatters:
0 - no information (default)
1 - balanced setup and iteration information
2 - diagnostic information
tech:debug (debug)
0*/1: whether to assist testing & debugging, e.g., by outputting
auxiliary information.
tech:logfile (logfile)
Log file name.
tech:lpdisplay (display, lpdisplay)
Frequency of displaying LP progress information:
0 - never (default)
1 - each factorization
2 - each iteration
tech:mipdisplay (mipdisplay)
Frequency of displaying branch-and-bound information:
0 - no node log displayed (default)
1 - each integer feasible solution
2 - every "mipinterval" nodes
3 - same as 2 plus cutting planes info and info about new incumbents
found through MIP starts
4 - same as 3, plus LP root relaxation info (according to "display")
5 - same as 4, plus LP subproblems (according to "display")
tech:mipinterval (mipinterval)
Frequency of node logging for "tech::mipdisplay" >=2:
0 - automatic (default)
n > 0 - every n nodes and every incumbent
n < 0 - new incumbents and less info the more negative n is
tech:optionfile (optionfile, option:file)
Name of an AMPL solver option file to read (surrounded by 'single' or
"double" quotes if the name contains blanks). Lines that start with #
are ignored. Otherwise, each nonempty line should contain "name=value",
e.g., "lim:iter=500".
tech:outlev (outlev)
Whether to write CPLEX log lines (chatter) to stdout,for granular
control see "tech:lpdisplay", "tech:mipdisplay",
"tech:bardisplay".Values:
0 - no output (default)
1 - equivalent to "bardisplay"=1, "display"=1, "mipdisplay"=3
2 - equivalent to "bardisplay"=2, "display"=2, "mipdisplay"=5
tech:reporttimes (reporttimes, report_times)
0*/1: Set to 1 to return the solution times in the problem suffixes
'time_solver', 'time_setup' and 'time' and in the solver message.
'time'= 'time_solver'+'time_setup' is a measure of the total time spent
in the solver driver; all times are wall times.
tech:threads (threads)
How many threads to use when using the barrier algorithm
or solving MIP problems; default 0 ==> automatic choice.
tech:timing (timing)
0*/1: Whether to display timings for the run.
tech:version (version)
Single-word phrase: report version details before solving the problem.
tech:wantsol (wantsol)
In a stand-alone invocation (no "-AMPL" on the command line), what
solution information to write. Sum of
1 - Write ".sol" file
2 - Primal variables to stdout
4 - Dual variables to stdout
8 - Suppress solution message.
tech:writegraph (cvt:writegraph, writegraph, exportgraph)
File to export conversion graph. Format: JSON Lines.
tech:writemodel (writeprob, writemodel, tech:exportfile)
Specifies files where to export the model before solving (repeat the
option for several files.) File name extensions can be ".lp[.7z]",
".mps", etc.
tech:writemodelonly (justwriteprob, justwritemodel)
Specifies files where to export the model, no solving (option can be
repeated.) File extensions can be ".dlp", ".mps", etc.
tech:writesolution (writesol, writesolution)
Specifies the names of files where to export the solution and/or other
result files in solver's native formats. Option can be repeated. File
name extensions can be ".sol[.tar.gz]", ".json", ".bas", ".ilp", etc.